The imaging process of a laser printer, which is composed of a process cartridge 100 as a basic core component, is shown in FIG. 1. The surface of a photosensitive drum 101 is evenly charged by a charging roller 102. A laser scanner 103 emits a modulated laser beam 104 containing image information to an outer cylindrical surface of the photosensitive drum 101. After illumination of the laser beam 104, a static charge distribution pattern with distribution difference, that is, an electrostatic latent image corresponding to the image to be copied, is formed on the cylindrical surface of the photosensitive drum 101. Then, a developer such as toner 106 transferred by a developing roller 105 is attracted to the cylindrical surface of the photosensitive drum 101 after the thickness thereof is regulated by a toner blade 113, covers the aforementioned electrostatic latent image and converts the same into a visual image which can be observed with naked eyes. As the photosensitive drum 101 rotates, the visual image formed by the toner 106 on the surface of the photosensitive drum is transferred to a position where a transfer roller 107 is located. Under the transfer voltage carried by the transfer roller 107, the toner in the form of the visual image is transferred to the surface of a recording medium 108 such as paper. After heated by a heating roller 111 and pressurized by a pressure roller 112, the toner in the form of the visual image on the recording medium 108 permeates into the fiber layers of the recording medium 108, curing the visual image formed by the toner on the recording medium 108 permanently. After the visual image on the photosensitive drum 101 is transferred by the transfer roller 107, residual toner 109 attached to the transfer roller 107 is scraped off by a waster toner blade 110 into a waster toner collecting tank. After static electricity on the surface of the photosensitive drum 101 is removed by a static electricity removing device, the photosensitive drum 101 is returned to the standby state, free from static electricity and toner. Then, a basic imaging workflow is finished. A desired image can be obtained by repeating the workflow.
For the above process cartridge 100, different manufacturers will produce products of different integration degrees in accordance with the functions and service lives of the components of the process cartridge 100, combined with their own R & D models. For example, the developing roller 105 responsible for developing and the toner blade 113 responsible for regulating the thickness of the toner layer may be integrated into an independent developing cartridge, which has the functions of storing a developer and transporting the same to the surface of the photosensitive drum 101. The photosensitive drum 101 may be pre-installed into the laser printer, or may be assembled with other components to form an electronic photographic imaging unit before being installed into the laser printer.
The document CN1580971 discloses a device for automatically detecting whether a developing cartridge mounted on an image forming apparatus has been used. The structure is a detection gear having a gear part with some missing teeth, and can irreversibly move from an unused position where the detection gear does not engage with the stirring rack gear, to a used position where the detection gear does not engage with the drive gear, through a drive force transmitting position where the detection gear engages with the drive gear, wherein the gear part engages with the detection gear when the detection gear is at the drive force transmitting position, the detection gear is provided with a contact member contacting a corresponding contacted member inside the machine, and when the developing cartridge is mounted to the image forming apparatus, a protrusion on the contact member contacts the contacted member to move the detection gear from the unused position to the drive force transmitting position.